1. Field of the Invention
This invention relates to a system for controlling a vehicle power sliding door, particularly to a system for controlling a power sliding door of a vehicle equipped with switching relays and a field effect transistor (FET) and capable of opening and closing a power sliding door by controlling the rotational speed and direction of rotation of a motor for driving the power sliding door.
2. Description of the Related Art
Japanese Patent Laid-Open Applications Hei 7(1995)-229344 and Hei 8(1996)-144633, for example, teach vehicle power sliding door control systems that are equipped with a sliding door installed to slide along one side of the vehicle and a motor or other source of driving power and is capable of opening and closing the sliding door automatically.
The diagram of FIG. 20 shows the basic configuration of the motor drive circuit for controlling the direction of rotation of the motor in the conventional systems (forward rotation for opening the door and reverse rotation for closing it). As shown in FIG. 20, the motor drive circuit includes a first relay 104 having a switching relay 100 switched by a coil 102 and a second relay 110 having a switching relay 106 switched by a coil 108.
The first and second relays 104 and 106 are connected to a first power source 112 that supplies them with a voltage of, for instance, about 12 V, and their outputs are connected to the positive and negative poles of a motor (designated M) 114. The coils 102 and 108 are connected to a second power source 116 that supplies them with a voltage of, for instance, about 12V and are further connected to the A (output port) and B (output port) of a controller 118. The controller 118 controls the level of the current passing through the coils to different combinations of Hi (to close the relays) and Lo (to open the relays). By this, as shown in FIG. 21, the direction of rotation (forward/reverse) of the motor 114 is controlled. C, D, E and F in FIG. 20 and FIG. 22 (referred to below) are detection resistances that indicate the driven state of the motor 114.
Japanese Patent Laid-Open Application Hei 9(1997)-328960 teaches a system in which an H bridge circuit configured by use of field effect transistors (FETs) produces a pulse signal for PWM (pulse-width modulation) -controlling current from a battery to enable directional and speed control of a motor.
The diagram of FIG. 22 shows the basic configuration of the motor drive circuit of the power sliding door control system using FETs.
In the motor drive circuit utilizing FETs, four FETs 120 and a motor 122 are connected as illustrated to configure a conventional H bridge circuit and the gates of the FETs 120 are connected to output ports A, B, C and D of a controller 124.
In this motor drive circuit, output of drive pulse signals from the output ports A, B, C and D as shown in FIG. 23 enables production of the indicated detected values at detection resistances E and F, i.e., enables control of motor 122 direction of rotation (forward rotation: solid line, reverse rotation: broken line) and rotational speed. As shown at the A and B outputs in the same figure, by outputting pulse signals it becomes possible to vary the motor rotational speed by PWM control.
Preferably, a vehicle power sliding door should be capable of being opened and closed at different speeds matched to the circumstances at the time of operation and should be capable of being opened and closed at the same speed even when the vehicle is parked or stopped on an incline. However, the foregoing systems utilizing switches, which are characterized by slow relay response of several milliseconds, are incapable of smooth sliding door operation.
While the system that controls the direction of motor rotation by operating FETs incorporated in the motor drive circuit is capable of PWM control, its use of multiple FETs increases the total amount of heat loss of the semiconductor devices to the point of requiring provision of a relatively large radiator (heat sink). The weight of the heat sink and its footprint on the circuit board are therefore proportionally larger. In addition, the size and weight of the power sliding door unit increases, leading to higher product cost.
In the circuit using FETs shown in FIG. 22, moreover, inadvertent reverse connection to the battery is liable to damage the FETs by producing heavy current flow through the FET parasitic diodes. Although it is conceivable to prevent such FET damage by inserting diodes or the like in the vicinity of the current source (battery), this would further increase the total amount of heat loss of the semiconductor devices.
An object of the present invention is therefore to overcome the aforesaid problems of the prior art by providing a system for controlling a vehicle power sliding door that is capable of controlling the direction of rotation of a power sliding door drive motor to effect opening and closing of the power sliding door with minimal total heat loss of semiconductor devices and that, by utilizing PWM control for varying motor rotational speed, lowers product cost by decreasing the size, weight and total number of components of the power sliding door unit.
Another object of the invention is to provide a system for controlling a vehicle power sliding door that is safe from FET damage even under heavy current flow caused, for example, by application of counter electromotive force.
Further, when detecting whether or not the motor drive circuit of such a vehicle power sliding door control system, which switches the direction (forward/reverse) of motor rotation by use of switching relays and regulates the motor rotational speed by use of the field effect transistor (FET), is operating normally, it is preferable to be able to check the drive circuit operation with simplest possible configuration and without need for operating the motor.
Still another object of the present invention is therefore to achieve such preferable checking capability by providing a system for detecting faulty operation of a vehicle power sliding door that enables current passing through a detection point to be detected and cut off without operating the motor and that is realized using a simply-configured motor drive circuit for opening and closing the vehicle power sliding door.
For realizing this object, in a first aspect of this invention provides a system for controlling a power sliding door of a vehicle, comprising: a motor supplied voltage from a power source mounted on the vehicle for opening or closing the power sliding door; a motor drive circuit for driving the motor having at least a switch for switching direction of rotation of the motor and a switching element for regulating the voltage to be supplied to the motor to change a speed of the motor rotation; and a motor-drive-circuit controller for outputting a command value to the motor drive circuit. In the first aspect the present invention provides a system for controlling a vehicle power sliding door that is capable of controlling the direction of rotation of a power sliding door drive motor to effect opening and closing of the power sliding door with minimal total heat loss of semiconductor devices and that, by utilizing PWM control for varying motor rotational speed, lowers product cost by decreasing the size, weight and total number of components of the power sliding door unit.
In a second aspect, the present invention provides the system further including: means for detecting an opening/closing speed of the power slide door; and wherein the motor-drive-circuit controller regulates the voltage to change the speed of the motor rotation such that the power sliding door is opened or closed at a speed inversely or substantially inversely proportional to the detected speed of the power sliding door. In the second aspect, the present invention provides a system for controlling a vehicle power sliding door that enables the power sliding door to be opened and closed at a steady speed even when, for example, opening/closing is conducted with the vehicle stopped on an incline.
In a third aspect, the present invention provides the system further including a branch which is connected to the ground through a diode such that the diode is connected with its anode on the ground side. In the third aspect, the present invention provides a system for controlling a vehicle power sliding door that is safe from FET damage even under heavy current flow caused, for example, by application of counter electromotive force.
In a fourth aspect, the present invention provides a system for detecting faulty operation of a power sliding door of a vehicle, comprising: a motor supplied voltage from a power source mounted on the vehicle for opening or closing the power sliding door; a power-sliding door controller provided in a motor current supply circuit for supplying current to the motor having at least a switch for switching direction of rotation of the motor and a switching element for regulating the voltage to be supplied to the motor to change a speed of the motor rotation; current detecting means for detecting supply of current to the motor; and faulty operation detecting means for detecting that faulty operation has occurred in the power-sliding door controller. In the fourth aspect, the present invention provides a system for detecting faulty operation of a vehicle power sliding door that, while being of simple configuration, enables abnormal current passing through the circuit to be detected and cut off without operating the motor.
In a fifth aspect, the present invention provides the system wherein the faulty operation detecting means detects that the faulty operation has occurred in the power-sliding door controller if the current detecting means detects the supply of current to the motor when predetermined outputs are supplied to the switch and the switch element. In the fifth aspect, the present invention provides a system for detecting faulty operation of a vehicle power sliding door that can efficiently detect and isolate shorts arising between the relay lines, between relay lines and ground, and so on.